Lower control arm position
Lower control arm position
(OP)
I'm furiously reading Staniforth et al and have a specific question I can't find explained.
All the examples for unequal A frames I see, set the lower arm position as horizontal at neutral bump/droop when viewed from the front. I've search photos from F1 etc. and always see the lower arm level with the ground.
For a road car would this always be the best position, or are there instances of an inclined lower arm, at normal ride height, being a better compromise?
Thanks, Colin.
All the examples for unequal A frames I see, set the lower arm position as horizontal at neutral bump/droop when viewed from the front. I've search photos from F1 etc. and always see the lower arm level with the ground.
For a road car would this always be the best position, or are there instances of an inclined lower arm, at normal ride height, being a better compromise?
Thanks, Colin.





RE: Lower control arm position
Norm
RE: Lower control arm position
Most serious off-road race trucks and buggies are also kept at or very close to level. For one thing, it's probably the only way you can go camber/straight/camber. It also provides lower overall suspension scrub and steering bias.
RE: Lower control arm position
RE: Lower control arm position
However, it makes the vehicle very sensitive to jacking - if you apply a lateral force at the CP then the inner end of the arm will be pushed up. Not good.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Lower control arm position
My readings so far seem to teach that it is the top arm length that controls negative camber gain through roll and so I wondered if the level neutral position for the lower arm really mattered that much.
RE: Lower control arm position
A-arm lenght, wheel travel lenght and a number of other
things, I may compromice using different cambercompensation curves, static camber settings and end up with a non-parallell to ground lower A-arm.
What I am trying to say is that it is a question related to circumstances.
Goran Malmberg
RE: Lower control arm position
RE: Lower control arm position
RE: Lower control arm position
You can have no change in camber with parallel, but not horizontal, upper and lower control arms of equal length.
It is difficult to evaluate the angle of only one control arm and learn much, however most of the production cars I have worked on ended up with the LCA going up as it went inboard.
-Joe